1. Field of the Invention
The present invention relates to a method and an apparatus for calibrating a terminal in a wireless communication system, and more particularly, to a method and apparatus for calibrating a Second Order Input Intercept Point (IIP2) by a terminal in a wireless communication system.
2. Description of the Related Art
The number of frequency bands defined in the current 3rd Generation Partnership Project (3GPP) standard is 30 or more and the frequency bands are configured variously from 690 MHz to 2.7 GHz. Further, a Long Term Evolution (LTE) technology corresponding to the 4th Generation wireless communication standard supports a larger amount of data transmission/reception without distortion in comparison with 3GPP. Accordingly, a terminal supporting LTE is required to function in networks of conventional 2G and 3G modes as well as in various frequency bands, where a free handover between the modes is needed. Further, one terminal is required to communicate with business operators in several countries through a link therebetween. That is, a terminal for current wireless communication is required to basically support a Multi Mode Multi Band (MMMB) function.
In order to support various modes and various bands, a communication terminal must include components of a Front End Module (FEM) in each frequency band, which results in complex terminal hardware and an increase in cost. Accordingly, there are efforts to simplify FEM components or implement a broadband solution.
Meanwhile, since a Surface Acoustic Wave (SAW) filter used by a reception side of a terminal may suppress a transmission output leakage signal or an interference signal other than a reception band, the use of a SAW filter may cause the least amount of deterioration in reception sensitivity. However, due to a problem such as complexity of hardware, the SAW filter cannot be used in all frequency bands of the reception side, and a current terminal does not use any filter other than a duplexer. However, when the reception side does not use the saw filter, an InterModulation Distortion 2 (IMD2) of a transmission leakage (TX leakage) signal is frequency down-converted to a baseband of the reception side and a Noise Figure (NF) capability of the reception side deteriorates. Accordingly, the IMD2 component due to the TX leakage signal is required to be as small as possible, which means as large an IIP2 as possible. The Input Intercept Point (IIP2) due to the IMD2 component is necessarily generated by nonlinearity and mismatching of a circuit and the size thereof may vary depending on a frequency or sample.